The present invention relates to a sliding member capable of invariably exhibiting the sliding property not only in dry and wet states but also in water, which is applicable for chains, bearings, guide rails and the like; and a method of manufacturing the sliding member.
Oil-retaining resin products in which lubricating oils are impregnated in porous resins have been used as sliding members since early times. In these resin products, porous resins have been generally manufactured using foaming agents. This causes disadvantages that the sizes of holes are relatively large; the retaining force of the impregnated lubricant is poor; the life period is short; and the durability of the resin product is small.
To improve the above disadvantages, there has been proposed a method, wherein a powder of a phenol resin continuous foaming body is bonded with a fiber material, a solid lubricant and the like by means of phenol resin, and the formed product thus obtained is impregnated with a liquid lubricant (see Examined Japanese Patent Publication No. 22361/1972).
The sliding member obtained by the above-described method, however, is disadvantageous in that when used in water, it is reduced in its lubricating characteristic because the liquid lubricant is floated in water and flows out of the sliding member.
A sliding member excellent in a water lubricating property is commercially available at present, in which a solid lubricant is bonded with carbon fiber by means of phenol resin.
The above-described prior art sliding material excellent in a water lubricating property in which a solid lubricant is bonded with carbon fiber by means of phenol resin is inconvenient in that, at the time of use in the dry state, the solid lubricant is easily dropped off because of the poor bonding force between the solid lubricant and the base material and thereby abnormal wear is rapidly generated; and, at the time of use in the wet state or water, the solid lubricant reacts with water or dissolved in water, resulting in the deteriorated lubricating property, or the solid lubricant flows in water from the sliding member, resulting in the shortened lubricating life.
To solve these problems, the present invention has been made, and an object of the present invention is to provide a sliding member used in dry and moistened states which is excellent in a lubricating performance and has a long wear life, wherein the drop-off of the solid lubricant is prevented at the time of use in the dry state, and the solid lubricant is prevented from reacting with water or flowing-out in water at the time of use in the wet state or water.